This invention applies generally to the recovery of viscous petroleum from natural formations. More specifically this invention relates to a process for separating bitumen from tar sands. While tar sand formations are specifically discussed here, it is well to consider that the technology described herein will also apply to viscous oil deposits, and to secondary or tertiary recovery processes after primary oil recovery. In other words, the invention is generally valuable for use on petroleum formations where problems of high viscosity and/or surface adhesion exist.
There are an estimated 26 billion barrels of tar of heavy oil in the tar sand deposits of Utah, but very little development of these deposits has occurred. These are rich deposits containing 8 to 14 percent bitumen, but they are more resistant to aqueous solution recovery techniques than are the Athabaska tar sands in Canada. U.S. Pat. No. 3,858,654 and Canadian Pat. No. 1,027,889 both teach processes for extracting tar from tar sands utilizing a combination of a polyphosphate compound combined with an alkalinity agent such as an ammonium or alkali metal hydroxide. Unfortunately, these methods provide relatively small yields when applied to Utah tar sands. For example, high concentrations of sodium pyrophosphate (20-30%) and sodium hydroxide (5%) give only partial separation of the bitumen from a Utah tar sand, even after boiling for extended periods. Clearly an improved method of recovery applicable to Utah tar sands would be of great economic importance. This is primarily the object of the present invention; however the method claimed herein will apply equally well to the Athabaska and other tar sand deposits throughout the world.